{"title":"Exceptionally strong coupling of defect emission in hexagonal boron nitride to stacking sequences","authors":"Song Li, Anton Pershin, Pei Li, Adam Gali","doi":"10.1038/s41699-024-00455-y","DOIUrl":"10.1038/s41699-024-00455-y","url":null,"abstract":"Van der Waals structures present a unique opportunity for tailoring material interfaces and integrating photonic functionalities. By precisely manipulating the twist angle and stacking sequences, it is possible to elegantly tune and functionalize the electronic and optical properties of layered van der Waals structures. Among these materials, two-dimensional hexagonal boron nitride (hBN) stands out for its remarkable optical properties and wide band gap, making it a promising host for solid state single photon emitters at room temperature. Previous investigations have demonstrated the observation of bright single photon emission in hBN across a wide range of wavelengths. In this study, we unveil an application of van der Waals technology in modulating their spectral shapes and brightness by carefully controlling the stacking sequences and polytypes. Our theoretical analysis reveals remarkably large variations in the Huang-Rhys factors–an indicator of the interaction between a defect and its surrounding lattice–reaching up to a factor of 3.3 for the same defect in different stacking sequences. We provide insights into the underlying mechanism behind these variations, shedding light on the design principles necessary to achieve rational and precise control of defect emission. This work paves the way for enhancing defect identification and facilitating the engineering of highly efficient single photon sources and qubits using van der Waals materials.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-8"},"PeriodicalIF":9.7,"publicationDate":"2024-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00455-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140016465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kyu Hyun Han, Seung-Hwan Kim, Seung-Geun Kim, Jong-Hyun Kim, Sungjoo Song, Hyun-Yong Yu
{"title":"Charge transfer mechanism for realization of double negative differential transconductance","authors":"Kyu Hyun Han, Seung-Hwan Kim, Seung-Geun Kim, Jong-Hyun Kim, Sungjoo Song, Hyun-Yong Yu","doi":"10.1038/s41699-024-00454-z","DOIUrl":"10.1038/s41699-024-00454-z","url":null,"abstract":"With development of information age, multi-valued logic (MVL) technology utilizing negative differential transconductance (NDT) phenomenon has drawn attention as next-generation computing technology that can replace binary logic. However, because conventional NDT devices primarily use ternary logic, multiple-peak NDT device is required for higher-radix MVL that can process more datasets. Here, van der Waals double-peak anti-ambipolar transistor (AAT) as NDT device was developed by utilizing peak voltage (Vpeak) modulation of NDT peak. For realization of quaternary logic, Vpeak modulation technology was developed through charge transfer mechanism from channel, thereby shifting NDT peak and increasing peak-to-valley current ratio (PVCR). Furthermore, Double-peak AAT was implemented through parallel configuration of two AATs with different Vpeak values. Finally, quaternary inverter with four widely stable logic states was implemented by utilizing the developed double-peak AAT with two distinct NDT peaks and high PVCR. This double-peak AAT is expected to contribute to the development of next-generation MVL technology capable of processing datasets.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-9"},"PeriodicalIF":9.7,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00454-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140000820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mickael L. Perrin, Anooja Jayaraj, Bhaskar Ghawri, Kenji Watanabe, Takashi Taniguchi, Daniele Passerone, Michel Calame, Jian Zhang
{"title":"Electric field tunable bandgap in twisted double trilayer graphene","authors":"Mickael L. Perrin, Anooja Jayaraj, Bhaskar Ghawri, Kenji Watanabe, Takashi Taniguchi, Daniele Passerone, Michel Calame, Jian Zhang","doi":"10.1038/s41699-024-00449-w","DOIUrl":"10.1038/s41699-024-00449-w","url":null,"abstract":"Twisted van der Waals heterostructures have recently emerged as a versatile platform for engineering interaction-driven, topological phenomena with a high degree of control and tunability. Since the initial discovery of correlated phases in twisted bilayer graphene, a wide range of moiré materials have emerged with fascinating electronic properties. While the field of twistronics has rapidly evolved and now includes a range of multi-layered systems, moiré systems comprised of double trilayer graphene remain elusive. Here, we report electrical transport measurements combined with tight-binding calculations in twisted double trilayer graphene (TDTLG). We demonstrate that small-angle TDTLG (~1.7−2.0∘) exhibits an intrinsic bandgap at the charge neutrality point. Moreover, by tuning the displacement field, we observe a continuous insulator-semimetal-insulator transition at the CNP, which is also captured by tight-binding calculations. These results establish TDTLG systems as a highly tunable platform for further exploration of magneto-transport and optoelectronic properties.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-8"},"PeriodicalIF":9.7,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00449-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139987485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kazue Orikasa, Cheol Park, Sang-Hyon Chu, Calista Lum, Tony Thomas, Tyler Dolmetsch, Luiza Benedetti, Arvind Agarwal
{"title":"Foam with direction: unraveling the anisotropic radiation shielding properties of 2D boron nitride nanoplatelet foams","authors":"Kazue Orikasa, Cheol Park, Sang-Hyon Chu, Calista Lum, Tony Thomas, Tyler Dolmetsch, Luiza Benedetti, Arvind Agarwal","doi":"10.1038/s41699-024-00451-2","DOIUrl":"10.1038/s41699-024-00451-2","url":null,"abstract":"Neutron radiation exposure is one of the main challenges faced during space missions. There is a critical need for advanced lightweight radiation shielding materials. Two-dimensional (2D) boron nitride nanoplatelets (BNNP) are excellent candidates for polymer matrix nanofillers due to their superior neutron shielding and thermal and mechanical properties. Furthermore, the 2D material anisotropic behavior unlocks the potential for composite property tailoring. This study fabricated ultra-lightweight lamellar BNNP foams (density 0.05 g cm–3 and 97.5% porous) via freeze-drying processing. The neutron shielding effectiveness or mass absorption coefficient of the BNNP foams with walls perpendicular to the direction of the radiation source was 14.47 cm2 g–1, while that of the foam with parallel configuration was only 8.51 cm2 g–1. The orientation-dependent neutron radiation shielding properties were modeled using the Beer-Lambert law for porous composite materials. The BNNP foam in this study has the potential to benefit advanced tailorable radiation shielding technologies for future aerospace missions.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-9"},"PeriodicalIF":9.7,"publicationDate":"2024-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00451-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139976627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Monolayer indium selenide: an indirect bandgap material exhibits efficient brightening of dark excitons","authors":"Naomi Tabudlong Paylaga, Chang-Ti Chou, Chia-Chun Lin, Takashi Taniguchi, Kenji Watanabe, Raman Sankar, Yang-hao Chan, Shao-Yu Chen, Wei-Hua Wang","doi":"10.1038/s41699-024-00450-3","DOIUrl":"10.1038/s41699-024-00450-3","url":null,"abstract":"Atomically thin indium selenide (InSe) exhibits a sombrero-like valence band, leading to distinctive excitonic behaviors. It is known that the indirect band gap of atomically thin InSe leads to a weak emission from the lowest-energy excitonic state (A peak). However, the A peak emission of monolayer (ML) InSe was observed to be either absent or very weak, rendering the nature of its excitonic states largely unknown. Intriguingly, we demonstrate that ML InSe exhibits pronounced PL emission because of the efficient brightening of the momentum-indirect dark excitons. The mechanism is attributed to acoustic phonon-assisted radiative recombination facilitated by strong exciton-acoustic phonon coupling and extended wavefunction in momentum space. Systematic analysis of layer-, power-, and temperature-dependent PL demonstrates that a carrier localization model can account for the asymmetric line shape of the lowest-energy excitonic emission for atomically thin InSe. Our work reveals that atomically thin InSe is a promising platform for manipulating the tightly bound dark excitons in two-dimensional semiconductor-based optoelectronic devices.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-9"},"PeriodicalIF":9.7,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00450-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139915801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Raman enhancement induced by exciton hybridization in molecules and 2D materials","authors":"Hikari Kitadai, Qishuo Tan, Lu Ping, Xi Ling","doi":"10.1038/s41699-024-00446-z","DOIUrl":"10.1038/s41699-024-00446-z","url":null,"abstract":"Surface-enhanced Raman spectroscopy (SERS) is a powerful technique for trace-level fingerprinting. Recently, layered two-dimensional (2D) materials have gained significant interest as SERS substrates for providing stable, uniform, and reproducible Raman enhancement with the potential for trace-level detection. Yet, the development of effective 2D SERS substrates is still hindered by the lack of fundamental understanding of the coupling mechanism between target molecules and substrates. Here, we report a systematic excitation-dependent Raman spectroscopy investigation on the coupling between 2D materials such as SnS2, MoS2, WSe2, and graphene and small organic molecules like rhodamine 6G (Rh 6G). Strong coupling between SnS2 and Rh 6G is found due to their degenerate excitons through Raman excitation profiles (REP), leading to the enhancement of Rh 6G vibrational modes that are observable down to 10−13 M. Our study shows that exciton coupling in the substrate-adsorbate complex plays a vital role in the Raman enhancement effect, opening a new route for designing SERS substrates for high sensitivity.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-8"},"PeriodicalIF":9.7,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00446-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139732419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Room temperature nonlocal detection of charge-spin interconversion in a topological insulator","authors":"Md. Anamul Hoque, Lars Sjöström, Dmitrii Khokhriakov, Bing Zhao, Saroj Prasad Dash","doi":"10.1038/s41699-024-00447-y","DOIUrl":"10.1038/s41699-024-00447-y","url":null,"abstract":"Topological insulators (TIs) are emerging materials for next-generation low-power nanoelectronic and spintronic device applications. TIs possess non-trivial spin-momentum locking features in the topological surface states in addition to the spin-Hall effect (SHE), and Rashba states due to high spin-orbit coupling (SOC) properties. These phenomena are vital for observing the charge-spin conversion (CSC) processes for spin-based memory, logic and quantum technologies. Although CSC has been observed in TIs by potentiometric measurements, reliable nonlocal detection has so far been limited to cryogenic temperatures up to T = 15 K. Here, we report nonlocal detection of CSC and its inverse effect in the TI compound Bi1.5Sb0.5Te1.7Se1.3 at room temperature using a van der Waals heterostructure with a graphene spin-valve device. The lateral nonlocal device design with graphene allows observation of both spin-switch and Hanle spin precession signals for generation, injection and detection of spin currents by the TI. Detailed bias- and gate-dependent measurements in different geometries prove the robustness of the CSC effects in the TI. These findings demonstrate the possibility of using topological materials to make all-electrical room-temperature spintronic devices.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-8"},"PeriodicalIF":9.7,"publicationDate":"2024-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00447-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139715268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Matej Sebek, Zeng Wang, Norton Glen West, Ming Yang, Darren Chi Jin Neo, Xiaodi Su, Shijie Wang, Jisheng Pan, Nguyen Thi Kim Thanh, Jinghua Teng
{"title":"Van der Waals enabled formation and integration of ultrathin high-κ dielectrics on 2D semiconductors","authors":"Matej Sebek, Zeng Wang, Norton Glen West, Ming Yang, Darren Chi Jin Neo, Xiaodi Su, Shijie Wang, Jisheng Pan, Nguyen Thi Kim Thanh, Jinghua Teng","doi":"10.1038/s41699-024-00443-2","DOIUrl":"10.1038/s41699-024-00443-2","url":null,"abstract":"A thin dielectric layer is an important constituent element in 2D materials-based electronics and photonics. Current methods of using hexagonal boron nitride (hBN) and direct deposition of dielectric layer induce either high leakage current or unintentional doping and defect. Here we report a technique for damaging free integration of dielectric layer to form high-quality van der Waals (vdW) heterostructure. The dielectric layer is grown by atomic layer deposition (ALD) on 2D materials and then deterministically transferred on the target 2D material. The much weaker binding energy between the ALD dielectric and the 2D materials enables the growth and exfoliation of the atomically thin dielectrics, which is confirmed by the X-ray photoelectron spectroscopy analyses and the density function theory calculations. The effectiveness of the technology is proven by the Raman and photoluminescence measurement on WS2 monolayer protected by the dielectric film through harsh plasma treatment. Furthermore, a 2D materials-based MOSFET is constructed as a demonstration of the viability of the technology for electronic device applications. The method produces flat surfaces and clean interfaces and would greatly benefit electronic and photonic applications as encapsulation or high-κ gate dielectric.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-9"},"PeriodicalIF":9.7,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00443-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139710642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yu. Yu. Illarionov, A. Karl, Q. Smets, B. Kaczer, T. Knobloch, L. Panarella, T. Schram, S. Brems, D. Cott, I. Asselberghs, T. Grasser
{"title":"Process implications on the stability and reliability of 300 mm FAB MoS2 field-effect transistors","authors":"Yu. Yu. Illarionov, A. Karl, Q. Smets, B. Kaczer, T. Knobloch, L. Panarella, T. Schram, S. Brems, D. Cott, I. Asselberghs, T. Grasser","doi":"10.1038/s41699-024-00445-0","DOIUrl":"10.1038/s41699-024-00445-0","url":null,"abstract":"Recent advances in fabricating field-effect transistors with MoS2 and other related two-dimensional (2D) semiconductors have inspired the industry to begin with the integration of these emerging technologies into FAB-compatible process flows. Just like in the lab research on 2D devices performed in the last decade, focus during development is typically put on pure technology-related issues, such as low-temperature growth methods of large-area 2D films on target substrates, damage-free transfer from sacrificial substrates and growth of top-gate oxides. With maturing technology, the problem of stability limitations caused by oxide traps is gradually coming into focus now. Thus, here we report an in-depth analysis of hysteresis and bias-temperature instabilities for MoS2 FETs fabricated using a 300 mm FAB-compatible process. By performing a comprehensive statistical analysis on devices with top gate lengths ranging between 18 nm and 10 μm, we demonstrate that aggressive scaling results in additional stability problems, likely caused by defective edges of the scaled top gates, in particular at higher operation temperatures. These are important insights for understanding and addressing the stability limitations in future nanoscale 2D FETs produced using FAB process lines.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-7"},"PeriodicalIF":9.7,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00445-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139676865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. B. Roldán, A. Cantudo, J. J. Torres, D. Maldonado, Yaqing Shen, Wenwen Zheng, Yue Yuan, M. Lanza
{"title":"Stochastic resonance in 2D materials based memristors","authors":"J. B. Roldán, A. Cantudo, J. J. Torres, D. Maldonado, Yaqing Shen, Wenwen Zheng, Yue Yuan, M. Lanza","doi":"10.1038/s41699-024-00444-1","DOIUrl":"10.1038/s41699-024-00444-1","url":null,"abstract":"Stochastic resonance is an essential phenomenon in neurobiology, it is connected to the constructive role of noise in the signals that take place in neuronal tissues, facilitating information communication, memory, etc. Memristive devices are known to be the cornerstone of hardware neuromorphic applications since they correctly mimic biological synapses in many different facets, such as short/long-term plasticity, spike-timing-dependent plasticity, pair-pulse facilitation, etc. Different types of neural networks can be built with circuit architectures based on memristive devices (mostly spiking neural networks and artificial neural networks). In this context, stochastic resonance is a critical issue to analyze in the memristive devices that will allow the fabrication of neuromorphic circuits. We do so here with h-BN based memristive devices from different perspectives. It is found that the devices we have fabricated and measured clearly show stochastic resonance behaviour. Consequently, neuromorphic applications can be developed to account for this effect, that describes a key issue in neurobiology with strong computational implications.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-6"},"PeriodicalIF":9.7,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00444-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139643963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}